Refresh vendored BB plugin SDK declarations

[colelawrence]

Summary

• regenerate the stale vendored BB SDK declarations for bb-ui-reference and sticky-notes
• align both plugins with the SDK 0.4.8 declarations already used by Agentation and Perspectives
• leave plugin source behavior unchanged

Validation

• all 126 tests pass
• all four workspace typechecks pass
• all four builds are regeneration-stable
• all four bb plugin types --check checks pass
• all four npm pack --dry-run checks pass
• git diff --check passes

This validates the repository-pinned bb-app@0.39.0 / SDK 0.4.8 boundary; unpublished newer fork APIs remain a separate integration concern.